This invention relates to cutting apparatus and more particularly to apparatus for grinding uprooted trees and tree stumps and the like into chips for facilitating the useful disposition of such materials.
When land is cleared for home or other types of construction, trees and tree stumps are removed and then disposed of. In the past, and until quite recently in many parts of the country, the trees and stumps were hawled to sanitary land fills and dumps for burying, and in time the wood decayed and disappeared into the environment.
Recently, however, in many parts of the country, with increasing density of population, the dumping sites have approached capacity and no new sites are available. As a consequence, restrictions are being proposed and implemented which limit severely what can be deposited in those sites; in many other cases, the sites have been closed, or closing dates in the near future have been set, and alternative locations, quite often at great distances, have been located and used, usually at substantial additional costs because of the transportation which is involved.
The disposal of trees and tree stumps by alternative methods is particularly expensive because the material is bulky and heavy with the result that transporting the material large distances becomes quite costly.
As a result, there have been efforts to provide apparatus capable of reducing the wood in the trees and stumps into a form which is more manageable and easier to dispose of. Most devices presently available for reducing such wood as described above operate at high speeds, typically 1500 to 1800 RPM. Devices operating at that rate of speed tend to have a very short useful life, especially that frequent blade changes are required. Efforts up to now to produce a slow turning machine, that is, at or under 50 RPM, have generally been unsuccessful and those claimed to be slow turning cost in excess of $300,000.
Several United States patents show the types of devices generally available to reduce this material.
In U.S. Pat. No. 3,570,566 to McCreery is shown a device for chipping away at a tree stump using a rotating disk with teeth embedded therein. Apparently it is not suitable for use on trees which have been cut down, nor is there provision for carrying away the debris. U.S. Pat. No. 4,062,498 to Szepaniak describes a device for removing and chipping thin trees and twigs, and is incapable of dealing with large trees and stumps.
U.S. Pat. No. 4,214,713 to Wright discloses a grinder for pulverizing leaves, twigs, and garden debris using a plurality of rotating lawn mower type blades. The patentee neither describes, nor does it seem likely, that it could be used for reducing large pieces as would be the case for full size trees and stumps.
However, patents to Harmon et al (U.S. Pat. No. 3,856,218), Cox (U.S. Pat. No. 3,929,294), and Palm et al (U.S. Pat. No. 4,168,035), do show equipment designed to crush or otherwise reduce tree trunks and the like. These devices are quite complicated and very expensive to construct. In addition, blade construction is such that they are expensive and difficult to replace; in this kind of apparatus, that can be a serious drawback since it is usually the blades which tend to wear out first and most frequently.